This disclosure relates to a fur brush roller used in a cleaning unit of an image forming apparatus, and the cleaning unit and the image forming apparatus provided with such a fur brush roller, and more specifically to a technology of maintaining cleaning performance of the fur brush roller over its long-term use.
In an image forming apparatus having a belt-like image carrier such as an intermediate transfer belt, a toner image primarily transferred onto a photosensitive drum is transferred onto a surface of the belt-like image carrier, and is further transferred onto recording paper by a secondary transfer roller. Then the color toner image transferred onto the recording paper is fixed on the recording paper at a fixing section through thermal compression. In such an image forming apparatus, foreign substances such as a toner and paper powders may remain on the surface of the image carrier after the secondary transfer processing, and these foreign substances are removed by the cleaning unit.
Typically, the cleaning unit includes: a fur brush roller making sliding contact with the image carrier; a sweep roller or a collection roller making sliding contact with the fur brush roller; and a scraper making sliding contact with the sweep roller. The transferred remaining toner has positive or negative electric charges, and is electrically absorbed and removed from the surface of the image carrier by the fur brush roller to which a bias with polarity opposite to that of the toner is applied. The toner removed from the surface of the image carrier by the fur brush roller is collected with electrostatic force and crimping force by the sweep roller. The transferred remaining toner collected by the sweep roller is scraped off by the scraper.
For example, there is a cleaning device which, as a result of forming a brush of a fur brush roller with a mixture of conductive yarns and insulation yarns, removes foreign substances on a surface of an image carrier by applying a bias with polarity opposite to charge polarity of a transferred remaining toner to the fur brush roller and electrostatically attracting the transferred remaining toner by the conductive yarns and adhesively collecting it, and also by charging the insulation yarns through friction by the transferred remaining toner and thereby electrostatically attracting the transferred remaining toner and adhesively collecting it.